Reactor coolant pump degradation can produce severe economic penalties for nuclear power plants which have to shut down for extended periods of time in response to a possible coolant pump failure. As a result, there is a strong economic incentive to develop and commercialize an effective apparatus to provide for early detection of coolant pump problems. Early detection of a coolant pump degradation would allow the reactor operator to manually trip the reactor before major pump damage occurred as opposed to the operator experiencing an automatic rapid shutdown of the reactor due to the loss of coolant caused by a damaged pump or a false alarm caused by a defective sensor. A controlled response would allow maintenance to be performed on the pump prior to failure or severe damage or to pinpoint a sensor problem and thus, limit the reactor down time.
The current general practice is to evaluate the condition of the reactor's coolant pump through the use of high/low limit checks of the pump's operating parameters. Using this system, when the coolant pump parameters read outside of a zone defined by the high/low values, an alarm is sounded, and the pump is shut down resulting in lost operating time. This type of analysis can result in a high number of false alarms and missed alarms when compared to an artificial intelligence technique which more closely analyzes the pump parameters as measured by a set of pump sensors.
Artificial intelligence techniques in an expert system continually survey and diagnose pump performance and operability as a means of detecting the early stages of pump degradation. Since most pumps are equipped with numerous sensors to monitor the condition of the pump, the sensors provide a good data base for use by the expert system. Applicants' expert pump diagnosis system continuously monitors and compares the digitized signals representing a variety of variables associated with the physical condition of the coolant pump: speed, vibration level, power, and discharge pressure. Variation of these variables is a possible indication of off-normal operation of the pump. Applicants' invention uses an expert system based on a mathematical comparison and analysis of multiple signals from a pair of nuclear reactor coolant pumps to analyze the condition of the coolant pump using the aforementioned input signals.
Accordingly, it is an object of this invention to provide an expert system for early detection of coolant pump degradation so as to provide the operator with information on this condition prior to pump failure.
A further object of this invention is to provide an expert system for determining sensor degradation as opposed to pump failure.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of instrumentalities and combinations particularly pointed out in the appended claims.